US Army
Since the dawn of time, men's creativity when it comes to hurting other men has known no bounds, and his fellow beasts have, on occasion, been called into this service. This has taken many different forms over the years.
In ancient times, the inhabitants of the Indus valley knew that the sight of a fully-equipped war elephant would terrify an enemy, as well as providing an unstoppable (to the weapons of the time) juggernaut with which to attack.